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ISO Tank Containers: Things To Know

ISO tank containers – also known as tanktainers – are frequently used to transport products that can’t be put in a standard storage box, for example liquids. Due to the nature of the cargo, they have specific features that they must meet in order to be fit for transporting products.

What Is An ISO Tank Container?

They are stainless steel, cylindrical unit fitted inside a standard 20ft frame. It is usually surrounded by protective layers to make it suitable for transporting liquids, and the steel cylinder is insulated with glass wool and Glass Reinforced Plastic. They are used for transporting a variety of liquids, powders or gases which includes everything from food, fuel, solvents, oil, and chemicals.

What differentiates them from standard tank models is that they are regulated by ISO standards. This means that they are manufactured, inspected and certified to international regulations making them a reliable and effective way to safely transport a range of fluid products. ISO is adapted to safely carry hazardous or non-hazardous materials and are manufactured with a protective tank lining to extend its life, especially when carrying corrosive liquids.

What Are The Different Types of ISO Models?

There are many different types of ISO models and the specification will vary depending on what needs to be transported. Generally, they can be categorised into the following types:

  • Food-grade tanks: These tanks are designed to transport food products only
  • Reefer tanks: A refrigerated tank that has the ability to keep transported products cold
  • Gas tank: A tank that has been built to transport gases
  • Silo or Storehouse tank: Silo, or Storehouse, tanks are used to transport powders or grains

Furthermore, ISO tanks have additional specified types as classified below:

  • T1 ISO tank: Built to transport light liquids
  • T4 ISO tank: Transports non-hazardous edible and non-edible oils
  • T11 ISO tank: Certified to transport non-hazardous chemicals
  • T14 ISO tank: Suitable for hazardous chemicals
  • T50 ISO tank: Transports liquefied petroleum gas and ammonia gas
  • T75 ISO tank: Designed for transporting liquefied gases
  • Rubber-lined ISO tank: Built to transport acid-based chemicals

What Are Their Specifications?

To be classified as an ISO container tank, it must conform to the regulations set by The International Organisation for Standardization (ISO), which consider aspects such as size, strength, and durability for its designated purpose. In addition, ISO tanks need to include a container safety certificate (CSC) issued by the manufacturer.

The international standard for an ISO tank frame is the same as a general purpose unit – 20ft length, 8ft wide and 8ft 6 inch in height, made from steel. Inside the tank frame sits the cylindrical pressure vessel which can then be further adapted depending on what substance it needs to transport.

Standard ISO tanks can transport from 17,500 to 26,000 litres in the cylinder. The tank itself needs to be at least 80% full to ensure the contents don’t surge too much during transit but less than 95% full to allow room for thermal expansion. The depth and pressure rating of the steel cylinder is dictated by the regulatory codes applied to it. The shell vessel needs to pass a minimum test pressure which is based on the tank’s assigned ‘T’ code.

Additional Safety Features on ISO Models

As the tanks can carry volatile substances, they must be checked every couple of years to ensure they are still compliant. With this in mind, ISO tanks are constructed with many additional safety features including:

  • Pressure relief valves to prevent any possible explosions that could be caused by excess pressure.
  • 500mm (or larger) manhole at the top of the unit to allow for easy inspection of the unit. The manhole is placed in the manlid spill box which is fitted with a rubber or PTFE gasket. Alternatively, the gasket will be made of an outer layer of PTFE that covers a nitrile rubber core for instances where a gas tight seal is needed.
  • A vapour valve that balances the pressure between the inside and outside of the tank or can be used for pressure discharge.
  • Burst discs which are made from metal and designed to burst to allow gas to escape and provide pressure relief when it hits a certain pressure limit.
  • Mounted thermometers so the temperature of the external shell can be checked.
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